Electric switch.



J. H. HALL,

ELECTRiC SWlTCH.

APPLICATION FILED MAR-18.

Patented Aug. 7, 1917..

UNITED s'ra'rns PATENT ornron.

JAY E. HALL, OF CLEVELAND, OHIO, ASSIGNOB, BY MESNE ASSIGNMENTS, TO THEELECTRIC CONTROLLER & MANUFACTURING CGMPANY, A CORPORATION OF OHIO.

ELECTRIC swrrcn.

Application filed March 18, 1913.

To all whom it may concern:

Be it known that I, JAY H. HALL, a citizen of the United States,residing at Cleveland, in the county of Cuyahoga and State of Ohio, haveinvented new and useful Improvements in Electric Switches, of which thefollowing is a specification.

My invention relates to magnetically-operated devices, and particularlyto magnetically-operated switches.

One of the objects of my invention is to provide a switch having asingle magnet or winding which has the characteristic of maintaining itscontacts open not only when the winding is not energized, but also whenit is energized above a certain value. The con tacts are closed when thecurrent in the winding is at or below this value. Another object is tocause the contacts to remain closed as long as the winding is energized.

Referring to the accompanying drawing, Figure 1 shows in side elevationone of the many forms of switches embodying my invention. Fig. 2 is awiring diagram showing the connections by which'a series of theseswitches may be used to control an electric motor;

On the drawing, the rectangular frame composed of magnetic material isprovided with the magnetizing winding 2' which controls the core orplunger 3. The upper end of the core carries the movable switch contact4: supported on a preferably non-magnetic stem. The contact 4.- whenlifted bridges the fixed contacts 5. The upper member of the frame 1contains an adjustable screw plug 6 composed of magnetic material andarranged in line with the core 3 to vary the length of the air-gap 12.

The lower member 9 of the frame 1 contains the screw 7 which isadjustable in line with the core and which forms a rest for the lowerend of the core when the winding 2 is not energized or is energizedabove a predetermined value as hereinafter described: By

adjusting the screw 7 the length of the airgap between the core 3 andthe frame-member 9 may be adjusted.

8 is a bar of ma etic material connected to the opposite si es of theframe between the top and bottom members thereof. I have shown the bar 8integral with the sides of the frame. The winding 2 may rest on thisbar, the core 3 extending through the same.

Specification of Letters Patent.

Serial No. 755,141.

The cross-section of the bar 8 is preferably smaller than that of theremainder of the bar 8, which furnishes the shortest return path forflux produced by the wlnding, can

not owing to its restricted cross-area, carry all the flux.Consequently, a portion of the flux is forced to flow through the lowerend Patented Aug. 7,1917.

of the core and the lower member 9 of the frame by way of the air-gap13. The magnetic pull across this air-gap assists gravity to hold thecore in the same position that it occupies when the winding is notenergized, that is, the magnetic pull across the gap 13 prevents thecore 3 from rising.

When the current in the winding is reduced to the said value, themagnetic pull in the gap 13 becomes so diminished that the core willthen be operated by the flux which traverses the ortion 8 of the frameand the air gap 12. hen the winding 2 is'energized with a current thatexceeds a prede termined value, the switch remains open, and whenthecurrent in the winding is reduced to that value, the switch operatesto close its contacts.

I have shown at 10 a closed conductor on the portion 8 of the frame,which may be used to cause the flux initially produced by the winding tobe dampened out of the portion 8 of the frame, and thereby to be made toenter the core through the frame member 9 and the air gap 13. Althoughthe closed conductors 10 may be found to improve the operation of theswitch, they are not essential for the successful operation thereof.

I have indicated at 11 a holding winding for the switch, which may beused to hold the switch closed after it has been closed by the winding2. The circuit of the holding winding 11 may be independent of thecircuit of the winding 2. If the winding 11 is connected in a shuntcircuit across a source of supply when the main switch is closed, itshould not be strong enough to close the switch, but strong enough tohold the switch closed after it has once been closed by the operatingwinding 2.

Referring to the wiring diagram in Fig.- 2, the motor to be controlledis shown at M; a main switch S is used to connect the motor system to asuitable source of supply; and the resistances R, R arearranged toregulate the current in the motor circuit during the acceleration of themotor. represent two of the switches shown in Fig. 1, the switch Shaving an operating winding only, whereasvthe switch S has an operatingwinding and a shunt holding windlng.

The operation of the system is as follows: Vhen the main switch S isclosed, the holding winding 11 of the switch S is energized, but asbefore explained, cannot cause the operation of the switch. The motorcircuit is from the positive through the motor M, the resistances R andR, and the operating winding of the switch S to the negative. The valueof the current at this time will be limited only by the resistances Rand R If it exceeds the value of current at which the switch S isadjusted to operate, the switch S will be locked open until the motorhas increased its speed and thereby dimin-- ished the current in themotor circuit. WVhen it will close its contacts, short-circuit the resistance R, and connect into the motor circuit the operating winding ofthe switch S The cutting out of the resistance R causes an increase'ofcurrent in the motor circuit which may be sufficient to lock the switchS open; but when the motor has further increased its speed, and therebycaused a reduction of current in themotor circuit, the switch S willoperate and short circuit the resistance R as well as the operatingwindingsof the switches S and S The switch S drops open, but the switchS remains closed, this being due to. the holding winding- 11. The motornow operates at normal full speed. p I

To stop the motor, the switch S is opened, whereupon the motor isdisconnected from the source of supply, the windingll becomesdeenergized, and the apparatus re- S and S llIaroh, A. D. 1913. I

winding is above a predetermined value, and

close its contacts when the current is reduced. a

I claim- 1. In an electromagnetic device, a'mag' netic circuit havingopposed poles, a magnetic shunt between the poles, and areciprocablecore, separated from one pole by an operating gap and fromthe otherpole by a lock;out gap, and a single winding surrounding "thecore and lying onthe opp'ositeside ofthe shunt from the look-out gap,the said shunt being of such restricted magnetic capacity as to forcesufiicient flux across the lock-out gap when the winding is energizedabove a predetermined value to overcome the magnetic pull on the coreacross'tthe operat ing gap. v 2. In an electromagnet c switch, sw ichcontacts, a magnetic circuit having. opposed poles, a magnetic shuntbetween the poles,-

and a reciprocable core,'separated= from one pole by an operating gapand from the other pole by a lock-out gap, and a single wlndlngsurrounding the core and ly ng onthe opposite side of the shunt'i'romthe" look-out gap, the said shunt being of such restricted magneticcapacity as to force sufli-- I cient flux across the look-out gap whenthe winding is energized. above a predetermined value to overcome themagnet-icpull on the core across the operating gap andto allow the fluxacross the operating gap to move the core sovas to close said contactswhen the energization of thewindin'g is reducedto the said value.

Signed at Cleveland, this' 15th day of JAYH. HALL.

Witnesses: V 1

RUTH H. BENNETT, H. M. DIEMER.

